| Abstract: |
Mild steel is an engineering material commonly employed in structural, automotive, and fabrication industries due to the presence of excellent properties. The mechanical properties of welded components made from mild steel have strong dependency on the welding current and heat input because they control the microstructural development in the weld region and HAZ. The inappropriate selection of these factors results in grain growth, hardness, and lower strengths.The objective of the present study is to experimentally evaluate the influence of welding current and the associated heat input on the mechanical properties of the joints obtained by Gas Tungsten Arc Welding (GTAW) on IS 2062 E250 grade mild steel. In the present experiment, the welding voltage and speed were kept constant during the welding process, and the welding current was varied from 120 A to 150 A. Correspondingly, the heat input varied from 1.68 to 2.10 kJ/mm. Mechanical properties of the GTA Welded Joints The experimental results suggest that the welding currents and heat inputs have a critical influence on the mechanical properties of the GTAW-welded mild steel joints. Lower heat inputs resulted in higher hardness along with increased brittleness, but higher heat inputs resulted in grain coarsening along with lower tensile strength. An optimum combination of tensile strength and hardness was obtained with a moderate range of heat inputs of around 1.82-1.96 kJ/mm, equivalent to a current range of 130-140 A.According to the research, an optimum heat input is required to be selected to obtain an optimum combination of properties such as strength and hardness of GTAW-welded mild steel joints to improve the quality of the welded joints. |
